The present invention relates to drug-containing pressure sensitive adhesive containing on one side, a backing, and on the other side, a release liner, (sometimes called a transdermal drug delivery device) and more particularly, to a method and apparatus for forming a transdermal drug device and scoring its liner to permit the liner to be easily removed from the adhesive carrying drug in one step.
Many apparatus and methods have been devised for continuously or intermittently scoring a release liner for use with transdermal drug-containing adhesive in order to permit the liner to be easily removed from the device immediately prior to its being used. One such method is to completely cut through the release liner. However, the typical procedure for the preparation of a transdermal drug delivery device is as follows: First, a dilution or suspension of the adhesive containing the drug is poured onto a flexible plastic intended to function as a disposable release liner. Next, a non-releasable backing material is applied over the adhesive. The result is a web containing an adhesive with a backing on one side and a disposable release liner on the other. A shaped device is then formed bY a peripheral cutting through all layers of the resulting web. The disposable release liner is then removed and a second, scored release liner is attached to the transdermal adhesive.
Alternatively, the liner can be first scored and assembled with the adhesive and the backing and then the assembly cut to the desired dimensions.
The purpose of the multi-step procedure for applying the backing and the release liner to the adhesive containing the drug is to avoid the problems encountered when a scored release liner is used in processing. If such a completely cut release liner is used prior to coating, the adhesive can pass through the release liner at the score causing equipment problems, cracking, separation and heat damage.
These prior art methods suffer from the disadvantage that the procedure for applying the release liner requires many steps. It thus has a tendency to be more expensive in large scale manufacturing than a procedure which would involve fewer steps.